Core drill



Sept. 21, 1937. A. c. cATLAND CORE DRILL Filed Aug. l2, 1936 2 Sheets-Sheet 1 @a 9,0% Z f 3 a m/ 27+@ 3f VVV 8 o w y 5 a Av... H...D.,....IH. w of? Z 7 OO w 4%@ W N5 y y 2 Y /l v Y 2 7%/ n U/w77 ...a d

sept. 21, 1937. A. ATLAND f 2,093,633

CORE DRILL b Filed Aug. l2, 1956 2 Sheets-Sheet 2 L/fp 2/ f/a /8 /M W' 32' o O o O 6/ 62 2g, 5P /6 -59 /2 l l l Il www, l/\// fre/7X0 Patented Sept. 21, l1937 UNITED STATES PATENT OFFICE CORE DRILL Application'Augllst 12, 1936, Serial No. 95,513

`1o claims. (cl. s55- 72) This invention relates to well drilling tools and relates more particularly to a well core drill. .A general object of this invention is to provide a simple, practical rotary core drill embodying 5 interchangeable bit heads 'and `core catchers.

Another object of this invention is tov provide a core drill that may be readily provided-with a bit head for use in hard earth formations or a bit head for use in softer formations and that may embody a dog type core ,catcher or a slip type core catcher, or both, when employing either type of bit head. The core drill of the present invention may be easily and quickly provided with either) type of bit head and with either form of core catcher, or with both forms of core catchers for use under practically any conditions.

' Another object of this invention is to provide a core drill embodying a novel and improved means for mounting or carrying a core catcher.

.i Another object of thisl invention is to provide a core drill in which thecirculation uid is conducted downwardly past the core catcher through an annular passage which leads directly to the fluid discharge ports in the bit head.

` y Another object of this invention is to provide a c ore drill embodying a simple, inexpensive sleeve for mounting and enclosing the core catcher, which sleeve also operatesto define the inner wall of the annular passage for conducting the cirfculation fluid past the core catcher to the bit head. I

Another object of this invention-is to provide a convertible core drillof the character mentioned that is-simple and inexpensive and that is rapid and elcient in operation.

The various objects and afeatures of my invention will be fully understood from the following detailed description o f typical preferred forms and applications of the invention, throughout which description reference is made tothe accompanying drawings, in wllich:

Fig.` 1 is a central longitudinal detailed sec-- tional View of the principal lower portion of the l core drill of the present invention 'embodying Aboth forms of core catchers and a roller rock bit.

Fig. 2 is a' central longitudinal detailed sectional View o1' the core drill embodying the pivoted dog' -type core catcher and the roller rock bit. Figs. d and 44 are transverse detailed sectional views J0 taken as indicatedby lines 3-3 and 4 4, respectively. on Fig. 1. Fig. 5 is a view similar to Fig. 2 showing the drill embodying a` drag type bit and Fig. 61s a transverse detailed sectional view `taken 4as indicated by line 8-6 on Fig. 5.

.55 `The core drill of the present invention is adapt- -shown) ed to embody a 'drag type bit for use in relatively soft or medium hard earth formations and may embody a vroller rock bit for 'use in harder. earth formations. Further, the core drill may .embody a pivoted dog type core catcher or a slip 5 type core catcher, or both, witheither form of bit head. In Figs.- 1, 3 and 4 of the drawings I have illustrated the drill embodyingboth types of core catchers and a roller rock bit. I Fig. 2 illustrates the drill embodying a dog type core catcher 10 and the roller rock bit 'and Fig. 5 illustrates the drill as provided with the dog type core catcher and. a drag type bit. I will rst describe the structure illustrated in Figs. 1, 3 and 4 of the drawings and then describe the manner in which 15 the drill may be modied by the removal and interchanging of the core catchers and the bit heads, as illustrated in the other gures.

'Ihe core drill-of the present invention illus- 'trated in Figs. 1,3 and4of the drawings comprises, 20

generally, the combination of an outer barrel II), abit head sub I I secured to the lower end of the outer barrel Ill', aroller type bit I2 on the sub I I, a sleeve I3 within the sub II, an inner barrel I4, a slip type corecatcher I5 mounted within the 25 sleeve I3, and a dog type core'catcher I 6 mountedA Within .the sleeve I3 and the bit I2.

'I'lle outer barrel lll of the core drill is adapted to be connected with the drilling string (not 'I'he outer barrel I0 is an elongate tubu- 30 lar structure which surrounds the inner barrel I4 and which carries the sub II and the parts connected therewith. In practice the outer barrel I0 may be connected with the rotary drilling string in the usual manner. In accordance with 35 the invention a tubular connecting member or sub I'I is provided on the lower end of the outer barrel III. vIn the arrangement illustrated in Figs. 1, 3 and 4 of the drawings the sub `I'I carries the sub II while in the arrangements illustrated in 4( Figs. 2 and 5 of the drawings the sub I'I carries the bits. .The sub I'I may be threaded on the lower end portion of tlfe outer barrel I0. Connecting means is provided onthe lower end of the sub I1 to receive the removable sub II and the 45 bits. In the -preferred construction illustrated this connecting means is in the form of a tapered threaded pin I8 formed on the. lower portion of the sub I'I. A downwardly facing external shoulder I9 may occur on the sub l1 at'the upper end 50 of its pin I8. An annular recess 20 may be provided in the lower end4 of the pin I8. The recess 20 is open at itsilower' end and is adapted toren ceive a part on the inner barrel I4, as will be hereinafter described.

The bit head sub I I is adapted to be removably secured to the sub I1 to carry the bit head I2 and to enclose the sleeve I3. The sub is a tubular member of substantially the same external diameter as the lower portion of the sub I1. A socket 2| is provided in the upper end of the tubular sub I| and is threaded to cooperate with the threaded pin I8. When the sub II is threaded on the pin I8 its upper end may bear against the shoulder I9. The sub II may be relatively long and is provided at its lower end with means for receiving or carrying the bit I2. A pin 22 is provided on the lower end of the sub I I. The pin 22 is of the same size as the pin I8 and has a thread similar to the thread of the pin I8. A downwardly facing annular shoulder 23 may be provided on the sub I I at the upper end of the pin 2-2. The longitudinal opening 24 of the sub II may be tapered or downwardly convergent between lts ends to provide ample stock or wall thickness for the pin 22. The opposite end portions of the opening 24 may be cylindrical.

The bit I2 is in the nature of a roller rock bit for use in hard earth formations and is operable to cut or form a core for reception in the inner barrel I4. The bit I2 includes atubular shoe or body 25 whose wall is thickened at its lower end. Circumferentially spaced recesses 26 enter the wall of the bit body 25 from its lower .end and receive cutters 21 and 21a. The cutters 21 and 21 project from the lower end of the bit body 25 to act on the formation of the bottom of the well bore. 'I'he cutters 21 are rotatable about downwardly yand inwardly inclined axes and act on the outer portion of the well bore to cut the bore to gauge. The cutters 21a are rotatable about downwardly and outwardly inclined axes and act on the inner portion of the well bore to form or trim the core for reception in the drill. Bearings 29 and 29*il respectively may rotatably support the cutters 21 and 21a on the pins 28 and 28a and suitable washers 30 and 30*3L may space the ends of the respective cutters from the walls or' the sockets 26.

The central longitudinal opening 3| of the tubular bit body 25 is proportioned to properly receive the core as trimmed by the inner cutters 21a. An annular recess 32 is provided in the wall of the opening 3| some distance above the lower end of the body 25 and uid ports 33 extend downwardly from the recess 32 to the `cutter carrying recesses 26. A socket 34 is provided in the upper end of the bit body 25 and may extend downwardly to the recess 32. The socket 34 is of the same size as the socket 2| in the sub I I and has a thread similar to the thread on the wall of the socket 2|. Thus the bit I2 may be threaded on the pin I8 of the sub I1 as illustrated in Fig. 2 of the drawings. In the assembly illustrated in Figs. 1, 3 and 4 of the drawings the pin 22 of the sub II is received or threaded in the socket 34 whereby the bit I2 lis secured to the lower end of the sub II. When the bit body 25 is properly threaded on the pin 22 its upper end may bear on the shoulder 23.

The sleeve I3 is provided to house or mount the core catcher I5 and to support the inner barrel I4. The sleeve I3 is preferably an integral tubular member as illustrated in the drawings. In accordance with the invention the sleeve I3 is removably arranged longitudinally in the sub to have its lower portion received in the bit body 25 and to have its upper end adjacent the lower end of the pin I8. 'I'he interior of the bit body 25 is formed to receive the lower portion of the sleeve I3 and to carry a portion of the core catcher I6. An annular recess 35 is provided in the wall of the opening 3| below the recess 32. The wall of the recess 35 is stepped to present a plurality of upwardly facing annular shoulders 36. The lower portion of the sleeve I3 extends into the upper end of the recess 35. 'Ihe lower end of the sleeve I3 may engage or bear on the uppermost shoulder 36. In practice the sleeve I3 may rotatably bear in the recess 35. 'Y

The sleeve I3 extends upwardly from the recess 35 to pass through the sub II with clearance. The exterior of the sleeve I3 substantially parallels the wall of the opening 24, that is it has cylindrical portions concentric with the cylindrical end portions of the opening 24 and a downwardly and inwardly tapering portion within the tapering portion of the opening 24. In accordance with the invention the sleeve I3 has substantial clearance in the opening 24 leaving an annular fluid passage 31. The passage 31 is continuous or uninterrupted and its lower end has direct full communication with the recess 32 which in turn communicates with the ports 33 whereby fluid passes directly from the annular passage 31 to the ports of the bit head I2. If desired or believed necessary a plurality of circumferentially spaced ribs 38' may be provided on the exterior of the sleeve I3 to cooperate with the wall of the opening 24 to centralize the sleeve I3 in the opening. The ribs 38 may be welded to the sleeve I3 as illustrated in the drawings. It is to be understood that the ribs 38 are not essential and may be eliminated, if desired. The interior of the sleeve I3 is shaped and formed to carry the core catcher I5 and to partially receive the core catcher I6. The longitudinal opening 39 of the sleeve I3 is proportioned to freely receive 'the core and is open at its opposite ends. The upper portion of the sleeve opening 39 is stepped or shouldered being provided with three vertically spaced annular shoulders 4I), 4I,` and 42. An annular recess 43 is provided in the lower end of the sleeve I3 to communicate with and form a continuation-of the space provided by the recess 35 in the blt body 25. It will be observed that the sleeve I3 is a simple, inexpensive part removably arranged in the sub II.

The inner barrel I4-is arranged longitudinally in the outer barrel I0 and is provided to receive the core cut by the bit I 2. The inner barrel I4 is preferably a thin walled tubular structure to be light in weight and to receive as large a core as possible. The inner barrel I4 extends through the barrel III and its sub I1 with substantial clearance to leave an annular fluid passage P. A bearing collar 44 is ilxed to the lower end of the inner barrel I4. In practice the collar 44 may be welded to the inner barrel I4. The collar 44 extends downwardly from the lower end of the inner barrel I4 and is rotatably received in the upper portion of the sleeve I3. The lower end of the collar I4 may rotatably bear on the shoulder 4I) to rotatably support the inner barrel I4 in the sleeve I3. A socket or recess 45 enters the collar 44 from its lower end 4to form a continuation of the space provided by the adjacent part of the sleeve opening 39. The collar 44 is provided with an external shoulder 46 and a hardened wear taking ring 41 is arranged on the shoulder 46. The hard wear taking ring 41 operates in the recess 20 and is adapted to rotatably bear upwardly against the upper wall of the recess 20 during operation of the drill. The collar 44 with its ring 41 is confined between the shoulder 40 and the upper wall or the recess 28 for free rotation whereby the inner barrel I4 may remain non-rotatable during the drilling operation. The collar 44 preferably projects upwardly into the sub I1|to stabilize the free inner barrel I 4.. A

plurality ofcircumferentially spaced ports 481s provided in the collar 44 to conduct the circulation fluid fromthe annular passage P in the sub I1, to the annular passage 31. The ports 48 are preferably inclined downwardly and outwardly. The lower end of the inner barrel I4 is open to v receive the core after its passage through the core type fully described and catcher I5.

The core catcher I is provided to assist in gripping and retaining the core to' recover the same when the drill is withdrawn from the well bore. The core catcher I5 is arranged within the sleeve I3 and is in the form of a slip type core catcher embodying gripping wedges or slips. The upper core catcher I5 may be of the generalI claimed in the co-pending application, Serial No. 34,649. The slip type core catcher I5 includes a free sleeve 49 within the sleeve I3, a body 5I below the sleeve 49, and slips 50 connected with the body 5I and operable through cooperation with the sleeve 49. The sleeve 4 9 is arranged within the upper the sleeve I3 to have its lower end at the shoulder tl and to have its upper portion extend into the recess 45. 'I'he sleeve 49 has a cylindrical exterior and fits Within the sleeve I3 and the recess t5 with suitable clearance to rotate or remain non-rotatable at will. The upper wall. of the recess 45 and the shoulder 4I prevent excessive longitudinal movement of the sleeve 49. A plurality of longitudinally extending guide-ways or grooves 52 is provided in the interior of the sleeve 39. The grooves 52 are equally spaced and extend downwardly from the upper end of the sleeve t5. The side walls of the grooves 52 may diverge inwardly toward the vertical center of the bit. The bottom walls of the grooves 52 are inclined downwardly and inwardly relative to the central vertical axis of the bit. Due to this inclination of their bottom walls the grooves 52 may terminate above the lower end of the sleeve 45. The body 5l of the core catcher l5 may be a simple annular member and is freely arranged in the sleeve I3 below the sleeve 53. The l,lower end ofI the sleeve 49 limits the upward movement of the body 5l while the engagement of the body 5I with the shoulder 42 prevents excessive downward movement of the body.

The slips 58 of the core catcher I5 are operable in the guide-Ways or grooves 52 and are wedgelike parts having inclined outer sides for cooperating with the inclined bottom walls of the grooves. The inner sides of the slips 53 are toothed to grip and support the core. 'I'he slips 58 are connected with the core catcher body 5l tomove longitudinally therewith and to move inwardly upon longitudinal movement of the sleeve 49 relative to the body 5I. Reins or spring arms 53 connect the slips y The spring arms 53 may be riveted to the interior of the body 5I and the outer sides of the slips 50. It is preferred-to embed or countersink the arms 53 in the slips 5I)l so that they do not interfere with the engagement of the slips with the walls o f the grooves 52. 'Rivets 54 may secure the spring arms 53 to the body 5I and the slips 50.

Means are provided on the body 5I .to resist relative vertical movement between the body and the core to retain the body in an up" position recovering the core.

portion of where the slips 5I! are inactive during downward movement of the drill and to resist upward movement of the slips 50 when thefdrill is raised so that the upwardly moving walls of the grooves 5.2 actuate the slips inwardly to gripv the core. This movement resisting means on the body 5I may be in the form of spring ngers 55. 'Ihe fingers 55 may be secured to the body 5I by the rivets 54 connecting the arms 53 with the body. 'I'he spring fingers 55 extend upwardly and inwardly from the body 5I and theirv upper end parts are turned inwardly to bear against the core. 'Ihe operation of the core catcher I5 will be hereinafter described.

'Ihe core catcher I8 is arrangedfwithin the bit I2 and is provided tov assist in gripping` and l'I'he core catcher I5 includes a ring-like body 51 received in the recess 35 and the recess 43. The body 51 is shaped and propor-` tionedto be free in the recesses 35 and 43 so that 59 extend through the lower portions of the openings 53 and pivotally support core gripping dogs project inwardly in the body' 68. The dogs 50 51 and their inner edges are sharpened to properly grip and support the core. The dogs 68 are adapted to pivot upwardly into the upper inner portions of the openings 58 when the core passes through the core catcher so that they do not interlere with the free reception of the core in the drill. Springs 6I surround the pins 59 and bear against the dogs 6I) to urge them downwardly' and inwardly into contact with the core. Cam faces 52 may be provided on the outer lower ends of the dogs 60 to cooperate with one of the shoulders 35 and assist in urging the dogs into proper gripping engagement with the cor The dogs 53 have fiat faces cooperating with the walls of the openings 53 to support the dogs in the core gripping. y and supporting position.

outer barrel Ill and its sub Ill and discharges fromthe ports 48 into the passage 31. The fluid ows downwardly through the passage 31 into the annular recess 32 and discharges from the recess 32 through the ports 33 to :liush the cutters 21 and It will be observed that the circulation uid flows downwardly around the sleeve I3 and the core catchers I5 and t6 and does not enter the core receiving opening of the drill to Wash away the core or sand up the core catchers. The passage 31 is continuous and annular throughout its length offering a minimum of resistance to liow of 4 the fiuid. The iiuid passing lthrough the passage 31 has little tendency to erode or cut away the drill parts. The ports 33 in the bit body 25 are short and straight, to discharge the i'luid directly against the cutters-21 and.21.

As the drilling progresses and the core *is formed the opening 3| receives the core. As the drill is fed downwardly the core is received in the core catcher I6, the sleeve opening 39, the core catcher I5 and ultimately in the inner barrel |4. As described above, the dogs 60 retract or pivot upwardly and outwardly to prevent the free passage of the core through the body 51. In a. like manner the spring ngers 55 may flex outwardly to pass the core. The engagement of the spring fingers 55 with the core tends to hold the body 5I upwardly as the drill is fed downwardly so that the slips 50 remain in the upper portions of the grooves 52. Thus the slips 50 remain retracted during the drilling operation. The core catcher body 51 is freely rotatable in the recesses 35 and 43 so that the engagement of the dogs 60 with the core may hold the core catcher I6 against turning. In a like manner the sleeve 49 and the body 5| are freely supported in the sleeve I3 so that the engagement of the spring ngers 55 with the core may hold these parts against turning during rotation of the drill. The inner barrel I4 is rotatably supported at its lower end through the collar 44 and the engagement of the core with the interior of the inner barrel may hold the inner barrel against rotation. Thus the drill does not embody any parts which score, groove, or cut into the core during rotation of the drill and the core remains intact and undamaged.

When suiilcient core has been cut the drilling action vis suspended and the drill is raised. Upon upward movement of the drill the dogs 60 pivot downwardly and inwardly into biting engagement with the core. 'Ihe springs 6I and the cam faces 62 assist in this movement of the dogs. Upon upward movement of the drill the spring fingers 55 engaging the core resist upward movement of the body 5| so that the sleeve 49 moves upwardly relative to the slips 50. When the sleeve 49 moves upwardly relative to the slips 50 the inclined walls of the grooves 52 cooperate with the slips 50 to force the slips inwardly into gripping contact with the core. Thus both core catchers I5 and I6 are simultaneously actuated to obtain gripping and supporting engagement with the core. 'I'he core catchers grip the core at longitudinally spaced points to effectively hold and support the same for recovery from the well ln the drill.l

Fig. 2 of the drawings illustrates the drill provided with the roller rock bit I2 and a single core catcher I6. When it is desired to employ the drill as illustrated in Fig. 2 of the drawings the blt body 25 is threaded directly on the pin I8 of the sub I1. Ithe event that the sleeve has been secured to the sub I1 as described above the sleeve |I is unthreaded from the pin I8 and the body 25 is unthreaded from the pin 22. 'I'he core catcher l5 and the sleeve I3 are removed together with the sub II. The dog type core catcher I6 is readily inserted in the bit body 25 to assume the position illustrated in Fig. 2 of the drawings. The bit body 25 is then threaded on the pin I8. It will be observed that the lower portion of the collar 44 is received in the recess 35 of the bit body 25 so that the inner barrel I4 is rotatably supported at its lower end within the body 25 and the lower portion of the sub I1. The upper wall of the recess 20 and the upper shoulder 36 limit the vertical movement of the collar 44 and the inner barrel I4. The ports 48 in thel collar 44 have their upper ends in communication with the interior of the sub I1 and their lower ends in direct communication with the recess 32 so that the circulation fluid is discharged from the sub |1 into the body 25 of the bit. From the above it will be seen that the sub |1 is adapted to directly carry the bit I2 and the bit body 25 is formed to receive the collar 44 when threaded on the pin I8.A Thus the bit I2 is interchangeable with the sub II and may be employed on the drill when the sub II and the core catcher I5 are not utilized.

Figs. 5 and 6 of the drawings illustrate the drill embodying a drag type bit I2 and the'single core catcher I6. The bit I2a includes a shoe or body 25a and cutting blades 10 project downwardly and outwardly from the body 25a. The body 25n may be similar, generally, to the body 25. The body 25a is a tubular member having a central vertical opening 3| to receive the core. A recess 35a corresponding in shape and size to the opening 35 is provided in the interior of the body 25a. A threaded socket 34a corresponding in size and shape to the socket 34 is provided in the upper end of the body 25a. An annular recess 32 similar to the recess 32 occurs at the interior of the body 25a between the socket 34a and the recess 35e. Fluid discharge ports 33W extend ldownwardly from the recess'32a to discharge the fluid into the well. The bit body 25u may be threaded directly on the sub I1 or may be threaded on the sub II in substitution for the bit I2 when the assembly illustrated in Figs. l, 3 and 4 of the drawings is to be employed. When the bit l2a is used as illustrated in Fig. 5 of the drawings the core ,catcher I6 is positioned in the recess 35n to have its upper portion received in the recess 45 in the collar 44. The lower portion of the collar 44 is received in the recess 35a and the upper portion of the collar is received in the recess 29 and the sub I1. Thus the core catcher I6 and the inner barrel are supported in substantially the same manner as in the assembly illustrated in Fig. 2.

The circulation fluid is passed downwardly through the passage P to flow through the ports 48 and the recess 32a to discharge from the ports 33a. The bit |2a illustrated in Fig. 5 of the drawings may be threaded on the pin 22 of the sub I I in the same manner as the bit I2. When secured to the sub |I the bit body 25HL receives the lower portion of the core catcher I6 and the lower portion of .the sleeve I3. The lower portion of the sleeve I3 is of the same diameter as the lower portion of the collar 44 to properly fit the recess 35a. Thus the bit I2?- may be interchanged for the bit I2 when the drill is provided with the single core catcher I6 and when the bit is provided .with the two catchers I5 and I6. 'I'he core drill provided by the present invention may be assembled for operation in practically any type of earth formation. The bits I2 and |2a may be interchangeably employed and the drill may be operated with either the core catcher I5, the core catcher I6, or both core catchers in combination with either bit I2 or |25.

Having described only typical preferred forms and applications of my invention, I do not wish to be limited or restricted to the specic details herein set forth, but wish to reserve to myself any variations or modiiications that may appear to those skilled in the art or fall within the scope of the following claims.

Having described my invention, I claim:

1. In a core drill having an internal shoulder, the combination of, a sleeve within the drill adaptedvto seat on the shoulder and spaced from the interior of the drill to leave an annular fluid passage therethrough, a second sleeve free within a sleeve arranged longitudinally within the drill .where it mayseat on the shoulderl and spaced from the interior wall of the `drill -to leave an annular fluid passage which discharges into said recess, a core catcher supported within the sleeve, and a collar on the lower end of the inner barrel resting mi the sleeve to support the inner barrel.

3. In a core drill having a bit head with an internal fluid recess and a shoulder below the recess, the combination of, a sleeve arranged longitudinally in the drill to extend through the recess and seat on said shoulder, there being an annular fluid conducting space between the interior of the drill and the sleeve extending between the upper and lower ends of the sleeve and in full communication with the said recess, an upwardly facing shoulder on the sleeve, and arotatable inner barrel seating downwardly on 4the shoulder.

,4, In a core drill having a bit head with an in'.- Vternal fluid recess and a shoulder below the recess, the combination of, a sleeve arranged longitudinally in the drill to extend through the recess and seat on said shoulder,there being an annular fluid conducting space between the interior of the drill and the sleeve extending between the upper and lower ends of the sleeve and in full communication with the said recess, there being a recess in the upper end of the sleeve, andan inner barrel extending longitudinally through the drill with clearance to leave an annular fluid passage communicating with said fluid space and rotatably bearing downwardly in the recess of the sleeve.

l `5. `In a core drill having a bit head with an internal fluid recess and a shoulder below the reof the drill and the sleeve'extending between the 50 upper and lower ends of' the sleeve and in full communication with the said recess, there being a recess in the upper end of the sleeve,` a core catcher'in the sleeve, and an inner barrel ex` tending longitudinally Vthrough the drill with 55 clearance to leave an annular fluid passage communicating with said fluid space and rotatably bearing downwardly inthe recess of the sleeve.

` catcher in the sleeve.

6. In a core drill having an internal shoulder and an internal fluid recess abovethe shoulder, a sleeve arranged longitudinally within the drill where it may seat on the shoulder and spaced from the interior wall of the drill to leave a continuous annular fluid passage communicating with -said recess, spaced ribs on the sleeve cooperating with the wall of the recess to hold the sleeve centralized in the drill, and a core catcher in the sleeve.

7. In a -core drill having an internal shoulder and an internal uid recess above the shoulder, a sleeve aranged longitudinally within the drill Where it may seat on the shoulder and spaced from the interior wall of the drill to leave an annular fluid passage communicating with the Yrecess, there being an upwardly facing shoulder in' the sleeve, an inner barrel -in the drill rotatably seated on the sleeve and having a downwardly facing shoulder, and a core catcher arranged in the sleeve between the two last mentioned shoulders.

8. In a core drill having a barrel and a blt head, the combination of, a tubular sub interposed between the barrel and bit head, the sub having a threaded socket in its upper end to receive the barrel, a threaded pin on the lower end of the sub of the same diameter as the socket to thread into the head, a sleeve extending longitudinally through the sub with clearance to leave an annular fluid passage therethro'ugh, and a core 9. In a core drill having a barrel and a bit head, the combination of, a tubular sub interposed between the barrel .and bit head, the` s ub having a threaded socket in its upperv end to receive the barrel, a threaded pin on the lower end of the sub of the same diameter as the socket to thread into the head, a sleeve extending longitudinaly through the sub with clearance to leave an annular fluid passage therethrough, an inner barrel rotatably supported on the sleeve to extend upwardly through the rst mentioned barrel, and a core catcher in the sleeve.

10. In a core drill having a barrel and a bit head, the combination of, a tubular sub inter posedbetween the barrel and bit head, the sub having a threaded socket in its upper end to receive the barrel, a threaded pin on the lower end of the sub of the same diameter as the socket to thread into the, head, a sleeve extending longitudinally through the sub with clearance to leave an annular fluid passage therethrough, ribs on the sleeve holding the sleeve centralized in the sub, and a core catcher in the sleeve.

, ALFRED C. CATLAND. 

